class Solution {
    public int singleNumber(int[] nums) {
        int ans = 0;
        for(int num:nums){
            ans ^= num;
        }
        return ans;
    }
}
public class TestHeap {
    public int[] elem;
    public int usedSize;
    public TestHeap(){
        this.elem = new int[10];
    }

    public void creatHeap(int[] array){

    }
}
